Leibfried, in U.S. Pat. Nos. 4,900,779, 4,902,731 and 5,013,809, and Bard and Burnier in U.S. Pat. Nos. 5,008,360 and 5,068,303, describe crosslinked organosilicon polymers and crosslinkable organosilicon prepolymers comprising alternating polycyclic hydrocarbon residues and cyclic polysiloxane or siloxysilane residues linked through carbon-to-silicon bonds. These polymers are useful, for example, in structural and electronic applications.
Although cyclic trisiloxanes were disclosed for use in the preparation of organosilicon polymers and prepolymers in U.S. Pat. No. 5,013,809 (Leibfried) and in Research Disclosure 326103 (June, 1991), these cyclic trisiloxanes were required to have two or more hydrogen atoms bound to silicon. Only cyclosiloxanes containing four or more silicon atoms were used in the preparation of these polymers and prepolymers, because cyclotrisiloxanes are not readily available and are unstable. It is also known that cyclotrisiloxanes with hydrogen atoms and methyl groups bonded to every silicon atom are not storage-stable.
Cyclopolysiloxanes in which some of the Si atoms are substituted with unsaturated polycyclic groups have been disclosed in U.S. Pat. No. 4,599,440, e.g., the reaction product of pentamethylcyclotrisiloxane and 5-ethylidenebicyclo(2,2,1)hept-2-ene. None of these compounds have unsaturated hydrocarbon groups on every silicon atom.